THIS!!! It always amazes me that people really think that Google and Amazon are just snooping on them just to obtain their data. I mean they can snoop on me all they want and they wouldn't get enough data to put on 1/4 sheet of paper. I don't think I am very valuable in the grand scheme of things. Most places we do business with know so much more about us. Hell one of the biggest credit reporting agencies allowed our data to breeched and we still don't know the real extent of that. I have all my credit reports locked and use a monitoring service, but if you do anything these days your info is out there.
There's way more data available about you than you realize. That quarter sheet of paper probably leads to enough info about you to fill 30 pages. You're just thinking about your transactions, but there's way more to it than just what you bought, in the case of Amazon, or what you searched for, in the case of Google.
At least Amazon gives you the option to turn it on or off, many times Apple adds stuff like this and you are stuck with it rather you like it or not because they never want to give options.
I doubt anything is ever turned off with Amazon, Google, FB, Twitherd, or whatever. Its simply obscured to the end user. Those companies gather and keep large amounts of data on people who aren't even members of their services (thanks to bonehead friends and business contacts who upload their contact lists), so why wouldn't they gather and keep even more about people who are members? Facebook has already been caught at this.
Apple of late has indeed been worrying me. For a privacy-forward company, Apple is remarkable at accidentally-on-purpose leaving all those things on "opt-out" on new phones. Health, iCloud backup and photos, Find My iPhone, Find My Friends, Location Services, etc. Every time I buy a new iPhone I have to badger the sales drone into leaving the phone in the box and letting me set it up so I can turn all that stuff off before I restore the info.
I recently logged into my iCloud account on someone else's phone, just so I could access my mail and texts. For some reason when you log into a different account on any iDevice since iOS 10, it "helpfully" turns on iCloud photo library and equally helpfully uploads the photos on that device to the new account. I refuse to use iCloud or any other service for photos or cloud backup, and due to this "feature" suddenly there were photos in my iCloud that have nothing to do with me. I logged out in a panic, and went into iCloud on my local machine, but it wouldn't let me delete the photos unless I signed back in on the device that uploaded the pics.
Also, I can't delete the Health app from any of my phones, and the data size of the Health app on each of them has grown over time even though I don't use any of the fitness tracking. So where is the data coming from?